Thermal energy storage systems and methods for use with solar power generation systems

ABSTRACT

Various arrangements are provided related to thermal energy coordination systems. A thermal energy coordination system may analyze solar irradiance measurements to identify an overgeneration solar energy event. The system may activate a thermal energy storage event to coincide with the overgeneration solar energy event at the plurality of solar panels. The system, which can include many network-enabled smart thermostats, may control air conditioners or other HVAC system within various structures. The system may determine a time to initiate cooling and a temperature to which to cool the structure based upon the received indication of the thermal energy storage event. Cooling may be initiated by the system based on the determined time and the determined temperature in response to the received indication of the thermal energy storage event

BACKGROUND

Peak demand events, including steep ramps, on an electrical grid havesignificant effects. Electricity providers must have sufficient capacityto deal with daily peak demand events, which typically occur around 6-8PM. To handle such peak demand events, an electricity service providermay need to use one or more power sources to meet the demand that areless efficient but can be activated quickly, such as natural gas powerplants. Further, a peak demand event may place a significant strain onan electrical grid, possibly causing component failure. If theelectrical grid experiences less demand during a peak demand event,fewer power sources may need to be activated or, possibly, built and thestrain on the electrical grid as well as power source emissions may bereduced.

SUMMARY

Various systems and methods related to thermal energy storage systemsare presented.

In some embodiments of such a system, a plurality of pyranometers arepresent. The plurality of pyranometers are physically distributed in avicinity of a plurality of solar panels, the plurality of pyranometerssupplying a thermal energy coordination system with a plurality of solarirradiance measurements. The system may include the thermal energycoordination system. The thermal energy coordination system may beconfigured to receive the plurality of solar irradiance measurements.The thermal energy coordination system may be configured to analyze theplurality of solar irradiance measurements to predict an overgenerationsolar energy event. The thermal energy coordination system may beconfigured to activate, to coincide with the overgeneration solar energyevent at the plurality of solar panels, a thermal energy storage event,The thermal energy coordination system may be configured to transmit, toat least a subset of a plurality of network-enabled smart thermostats,the indication of the thermal energy storage event in response toactivating the thermal energy storage event. The thermal energy storagesystem may include the plurality of network-enabled smart thermostatsinstalled at a plurality of structures. Each network-enabled smartthermostat of the plurality of network-enabled smart thermostats may beconfigured to: control an air conditioner within a structure in whichthe network-enabled smart thermostat is installed based upon a measuredtemperature and a setpoint temperature; determine a time to initiatecooling and a temperature to which to cool the structure based upon thereceived indication of the thermal energy storage event; and initiatecooling by the air conditioner based on the determined time and thedetermined temperature in response to the received indication of thethermal energy storage event.

Embodiments of such a system may include one or more of the followingfeatures: The thermal energy coordination system may be configured topredict a time period during which the overgeneration solar energy eventwill occur at least partially based on the plurality of solar irradiancemeasurements, wherein the indication of the thermal energy storage eventindicates the time. Electricity generated by the plurality of solarpanels may be used to directly power air conditioners controlled by theplurality of network-enabled smart thermostats without using a batterycharged by one or more solar panels of the plurality of solar panels forstorage of the electricity. Each network-enabled smart thermostat of theplurality of network-enabled smart thermostats may be further configuredto transmit a thermal mass value to the thermal energy coordinationsystem such that the thermal energy coordination system receives aplurality of thermal mass values from the plurality of network-enabledsmart thermostats. The thermal energy coordination system may beconfigured to select the subset of the plurality of network-enabledsmart thermostats based on the plurality of thermal mass values. Thethermal energy storage event may indicate a time period during which anamount of energy used for cooling by the subset of the plurality ofnetwork-enabled smart thermostats is to be decreased. Eachnetwork-enabled smart thermostat of the plurality of network-enabledsmart thermostats may be configured to: decrease a runtime of the airconditioner controlled by the network-enabled smart thermostat duringthe time period. Each network-enabled smart thermostat of the pluralityof network-enabled smart thermostats may be further configured to ceaseactivating the air conditioner controlled by the network-enabled smartthermostat during the time period.

Additionally or alternatively, embodiments of such a system may includeone or more of the following features: The plurality of solar panels mayinclude: a first subset of solar panels located at a grid-level solarfacility and a second subset of solar panels that are distributed at asubset of the plurality of structures. The thermal energy coordinationsystem may be configured to activate the thermal energy storage event isbased on a difference between electricity generation by the plurality ofsolar panels and a grid electrical load. The thermal energy coordinationsystem may be configured to receive, from each network-enabled smartthermostat of a superset of network-enabled smart thermostats thatcomprises the plurality of network-enabled smart thermostats, a thermalmass value for the structure at which the network-enabled smartthermostat is installed, such that the thermal energy coordinationsystem receives a plurality of thermal mass values from the superset ofnetwork-enabled smart thermostats. The thermal energy coordinationsystem may be configured to select the plurality of network-enabledsmart thermostats from the superset as eligible to participate as partof the thermal energy storage system based on the received plurality ofthermal mass values.

In some embodiments, a method for using a thermal energy coordinationserver system is presented. The method may include identifying, by thethermal energy coordination server system, a power overgeneration eventthat includes power overgeneration due at least in part to powergenerated by a plurality of solar panels. The method may includepredicting, by the thermal energy coordination server system, a peakdemand event expected to occur on a same day as the power overgenerationevent. The method may include activating a thermal energy storage eventin response to the power overgeneration event and the peak demand eventexpected to occur on the same day. The method may include transmitting,by the thermal energy coordination server system, to at least a subsetof a plurality of network-enabled smart thermostats, an indication ofthe thermal energy storage event in response to activating the thermalenergy storage event, wherein the thermal energy storage event comprisesan indication of a first time period of the power overgeneration eventand an indication a second time period of the peak demand event.

Embodiments of such a method may include one or more of the followingfeatures: The method may include determining, by each network-enabledsmart thermostat of the plurality of network-enabled smart thermostats,a time to initiate cooling and a temperature to which to cool anassociated structure based upon thermal energy storage event. The methodmay include initiating, by each network-enabled smart thermostat of theplurality of network-enabled smart thermostats, cooling based on thedetermined time and the determined temperature in response to thereceived indication of the thermal energy storage event. Identifying thepower overgeneration event may include analyzing, by the thermal energycoordination server system, a plurality of solar irradiance measurementsto determine the first time period during which the power overgenerationevent will occur. The method may include receiving, by the thermalenergy coordination server system, from each network-enabled smartthermostat of the plurality of network-enabled smart thermostats, athermal mass value such that the thermal energy coordination serversystem receives a plurality of thermal mass values from the plurality ofnetwork-enabled smart thermostats. The method may include selecting, bythe thermal energy coordination server system, the subset of theplurality of network-enabled smart thermostats based on the plurality ofthermal mass values. The method may include ceasing, by eachnetwork-enabled smart thermostat of at least the subset of the pluralityof network-enabled smart thermostats, to activate an air conditionercontrolled by the network-enabled smart thermostat during the secondtime period of the peak demand event. Identifying the powerovergeneration event may include determining a difference betweenpredicted electricity generation and a grid electrical load. The methodmay include receiving, from each network-enabled smart thermostat of asuperset of network-enabled smart thermostats, a thermal mass value fora structure at which the network-enabled smart thermostat is installed,such that the thermal energy coordination server system receives aplurality of thermal mass values from the superset of network-enabledsmart thermostats. The method may include selecting, by the thermalenergy coordination server system, the plurality of network-enabledsmart thermostats from the superset as eligible to participate as partof the thermal energy coordination server system based on the receivedplurality of thermal mass values.

In some embodiments, a non-transitory processor-readable mediumcomprising processor-readable instructions is presented. Theinstructions may cause the one or more processors to identify a powerovergeneration event expected to occur that includes powerovergeneration due at least in part to power generated by a plurality ofsolar panels, The instructions may cause the one or more processors topredict a peak demand event expected to occur later on a same day as thepower overgeneration event, The instructions may cause the one or moreprocessors to activate a thermal energy storage event in response to thepower overgeneration event and the peak demand event expected to occuron the same day. The instructions may cause the one or more processorsto transmit to a subset of a plurality of network-enabled smartthermostats, an indication of the thermal energy storage event inresponse to activating the thermal energy storage event, wherein thethermal energy storage event comprises an indication of a first timeperiod of the power overgeneration event and an indication a second timeperiod of the peak demand event.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of variousembodiments may be realized by reference to the following figures. Inthe appended figures, similar components or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIG. 1A illustrates a graph of an example of solar output and typicalload for an electrical grid.

FIG. 1B illustrates a graph of an example of grid-level demand and timefor an electrical grid.

FIG. 2 illustrates an embodiment of a solar-powered thermal energystorage system.

FIG. 3 illustrates another embodiment of a solar-powered thermal energystorage system that includes distributed solar panels.

FIG. 4 illustrates another embodiment of a solar-powered thermal energystorage system that uses a third-party platform to manage communicationwith network-enabled smart thermostats.

FIG. 5 illustrates an embodiment of a method for using a thermal energystorage system.

FIG. 6 illustrates another embodiment of a method for using a thermalenergy storage system.

FIG. 7 illustrates an embodiment of a method for a network-enabled smartthermostat to participate as part of a thermal energy storage system.

FIG. 8 illustrates an embodiment of a method for registering anetwork-enabled smart thermostat to participate as part of a thermalenergy storage system.

FIG. 9 illustrates a computer system.

DETAILED DESCRIPTION

Many homes, apartment buildings, offices, warehouses, and businesses(collectively referred to as “structures”) have solar panels installedto generate electricity. Such electricity can be used locally at thestructure or can be output onto a utility's electrical grid for use atother locations. Also, utilities may operate or purchase electricityfrom large-scale solar farms, which are usually located a significantdistance from the structures that are supplied with the generatedelectricity. While a significant amount of electricity is generated bysolar panels on sunny days, generation of such solar energy is onlyuseful if there is sufficient demand being placed on the electricalgrid, especially if energy storage devices (e.g., grid-level orstructure-level batteries) are not deployed or used.

Solar intensity, the amount of energy being received from the sun,typically peaks several hours before peak demand occurs on an electricalgrid. The amount of solar energy being converted to electricity peakswith solar intensity but demand will likely not peak until several hourslater, such as during a daily peak demand event occurring between 6-8PM. Therefore, in order to increase the usefulness of electricity beinggenerated by solar panels, it would be useful to store such generatedelectricity until the time period when peak demand is occurring. Peakdemand is especially concerning due to power suppliers needing toconstruct power generation sources simply to meet worst-case peakdemand. For instance, a natural gas powered plant may be constructed tohandle a peak demand event that only occurs in the summer for severalhours during the week. Avoiding the building of such facilities—andtheir accompanying emissions—may be accomplished via the systems andmethods discussed herein. Energy storage, as used in this document, isdefined as: the reception or absorption of energy (the “charging” of thedistributed energy storage device), the energy being stored for a periodof time, and thereafter the stored energy being used or released (the“discharging” of the distributed energy storage device). Such storagecan be used as a form of demand response by decreasing demand upon anelectrical grid during the time of peak demand.

While electricity can be stored directly by devices such as batteries orcapacitors, electricity generated using solar panels may be storedindirectly in another form. One type of indirect storage of electricityis thermal storage. Thermal storage performed for a structure mayinvolve heating or cooling the interior environment of the structure.Since air conditioning consumes a significant amount of electricity andthe use of air conditioning tends to coincide with days of high solarintensity (and the associated high environmental temperatures), airconditioning represents a candidate for use in performing thermal energystorage. Further, such distributed thermal energy storage may havesignificant benefits over grid-level batteries or capacitors clusteredin single or limited locations. Thus, cost may be significantly lowerand batteries and capacitors run a risk of overheating and/or exploding.Such distributed energy storage significantly increases the number ofstorage locations ensuring that an adverse impact to any single locationdoes not affect the capacity or usefulness of the energy storage system.Such energy storage also avoids the hazardous materials or expensivemetals associated with some existing energy storage systems and devices.

When excess electricity is generated by solar panels, such energy may beconverted to thermal energy by pre-cooling the interior environment of astructure in anticipation of a demand response situation occurring inthe near-term future (e.g., within 5 hours). Such cooling may involvecooling the structure early compared to a temperature setpoint definedby a user and/or cooling the structure to a lower temperature thanrequested by the user. For instance, if a user has set his smartthermostat to have his home cooled to 75 degrees Fahrenheit by 8 PM, apre-cooling arrangement may bring the temperature of the home to thedesired temperature earlier than 8 PM and/or may cool the structure toseveral (e.g., 2, 5, 10) degrees below 75 degrees Fahrenheit. If peakdemand of electricity usage occurs at around 8 PM on the electricalgrid, by precooling the structure to decrease or eliminate the usage ofthe air conditioner during the time around peak usage, the structure haseffectively stored electricity as thermal energy to decrease peakelectricity usage.

The ability of a structure to store thermal energy is at least partiallydependent on how well the structure can maintain a temperaturedifferential between the structure's interior and the exteriorenvironment. The greater a structure is insulated, the more effectivethe structure will be at storing thermal energy, and, thus, the higherthe structure's thermal mass. In some situations, if a structure issufficiently insulated, it may be possible for the structure to beprecooled (by starting cooling earlier than needed and/or by cooling toa lower temperature) such that a time period coinciding with a peakdemand event can be fully avoided from having the air conditioner turnedon. The better insulated a structure is, the longer that energy can beeffectively stored by the structure (loss is decreased). Further, duringthe demand response event, when an air conditioner is to be activatedless often, comfort may be maintained longer because the increasedinsulation helps prevent the interior temperature from rising rapidly.

The control of such a system may be based on measured or predicted solarintensity for a given day at locations where solar panels are located.Real time measurements, models, and/or predictions of the amount ofelectricity available to be generated and thermally stored (e.g., notneeded immediately on the grid or locally at a structure) may bedetermined. If greater than a threshold amount of solar-generatedelectricity is available for thermal storage, a structure-based thermalmass storage system may be engaged that relies on precooling manystructures by initiating cooling early (e.g., earlier than requested bya user) and/or cooling the structure to a lower temperature than set bya user. Such an arrangement may be enabled by network-basedcommunication with “smart” thermostats, such as the Nest® LearningThermostat. By storing the excess solar energy from earlier in the dayas thermal energy, the use of other forms of energy storage may bereduced or eliminated. For example, such a thermal energy storage systemmay help avoid the use of grid-level or structure-level batteries.

While the following description focuses on solar energy as the sourcefor preheating and precooling structures, it should be understood thatin various embodiments, the power source that contributes toovergeneration of power may be other than a solar source. For instance,wind energy may tend to peak during the night. Systems and method asdetailed below may be adapted to preheat or precool structures during adifferent timeframe based on overgeneration of power by an alternatepower source, such as a wind farm.

FIG. 1A illustrates a graph 100A of solar output and a typical dailyload on an electrical grid. On graph 100A, the solar output of one ormore solar-based power production facilities, at least on a clear day,roughly resembles a bell curve. Line 110 represents the megawatt outputof an exemplary solar power production facility. Maximum output isreached around noon and begins to significantly drop off around 4 PM.Line 120 represents an exemplary grid-wide load which the exemplarysolar-based power production facility may supply with power. The loadramps up at almost a linear rate through the day, peaking approximatelyat 6 PM and remaining substantially elevated until after 8 PM. Duringthis time period of 6 PM to 9 PM, the power generated by the exemplarysolar-based power production facility has decreased substantially due tothe setting sun.

While graph 100A is exemplary, it is common for an electrical grid toexperience peak demand between 6 PM and 9 PM (referred to as a “peakdemand event”). Further, it is common for power generated by solarpanels, whether installed at a structure or at a dedicated solar powergeneration facility, to reach a daily maximum output (“peak solargeneration event”) 3-6 hours earlier than the peak demand event. Sincethe peak solar generation event does not coincide with the peak demandevent, other power sources are typically used to provide power duringthe peak demand event, such as oil, natural gas, or diesel power plants,which can be relatively quickly brought online to begin powergeneration.

Since a daily peak solar generation event does not coincide with theday's later peak demand event, the electricity generated using solarpower must be stored if it is going to be used during the peak demandevent. One possible way of storing such power is using large-scale ordistributed batteries and/or capacitors. However, such an approach canrequire new and expensive specialized equipment. Rather, HVAC equipmentalready connected with the electrical grid may be used to store suchsolar energy as thermal energy in individual structures. By storing theenergy of electricity generated during the peak solar generation eventas thermal energy, energy savings can then be realized during the peakdemand event that occurs at least a few hours later in the day,effectively storing the solar-generated electricity.

FIG. 1B illustrates graph 100B, which represents an example ofgrid-level demand against time for an exemplary electrical grid. Ingraph 100B, a grid's demand is graphed on the y-axis against time on thex-axis. Lines are present for various years, including some years forwhich actual data is available (2012, 2013) and predictions for lateryears (2014-2020). During the approximate timeframe of 10 AM until 6:30PM, demand (net load) is decreased, especially as forecast in years 2014through 2020, due in large part to a significant amount of electricitybeing generated by solar panels. The electricity being generated bysolar panels, including those directly connected to structures'electrical systems, decreases the amount of demand on other sourcespresent on the electrical grid, resulting in possible overgeneration ofelectricity during time period 150.

Some power sources, such as coal and nuclear are typically thought of as“baseload” power sources that output a roughly consistent amount ofpower over time. Such power sources are inefficient to quickly bebrought online or offline. Therefore, despite solar panels producing asignificant amount of power during time period 150, such baseline powersources may continue producing near-constant amount of power, thusresulting in possible overgeneration events during which more power isavailable than is being used on the grid, even if “peaker” power sourcesare offline.

Peaker power sources refer to power sources that can relatively quicklybe brought online. Typically, a peaker power source is a natural gaspowered power plant that can be brought online for a short time per dayto help with peak demand events. The overgeneration events expected foryears 2014-2020 during time period 150 can actually exacerbate the peakdemand event of time period 160 by requiring a significant ramp up ofpower output in the 7-10 PM time window. For instance, in 2017-2020, aramp-up of about 13,000 Megawatts in power generation may be necessaryto supply the load on the electrical grid when transitioning from timeperiod 150 to time period 160.

By using structures as energy storage devices as detailed in thisdocument, the trough of graph 100B during time period 150 may be madeless severe (by using additional power during an overgeneration event)and the peak of graph 100B during time period 160 may be made lesssevere (by reducing power usage during the peak demand event).

FIG. 2 illustrates an embodiment of a solar-powered thermal energystorage system 200. Solar-powered thermal energy storage system 200 mayallow electricity generated using solar panels (and/or other sources) tobe stored as thermal energy at a distributed set of structures. Whilesolar-powered thermal energy storage system 200 may allow electricitygenerated by solar panels to be stored as thermal energy at a structure,it should also be understood that electricity generated from othersources may be stored as thermal energy instead or in addition tothermal energy generated using electricity directly from solar panels.Overgeneration of electricity from sources other than solar panels maybe due to the increased output of solar panels during a peak solargeneration event being able to power a significant portion of anelectrical grid's load.

Solar-powered thermal energy storage system 200 may include: solar powergeneration facility 210, thermal energy coordination system 220,electrical grid 230, network 235, network-enabled smart thermostat250-1, air-conditioner 242, and electric heater 244. Solar powergeneration facility 210 may represent a dedicated power generationfacility that generates electricity using many solar panels. Typically,such facilities are located a significant distance from the electricalload that such facilities power. Solar power generation facility 210 mayexperience a daily peak solar event where the power output of thefacilities solar panels reaches a maximum and then decreases. Solarpower generation facility 210 may provide electricity to electrical grid230.

Electrical grid 230 may serve to distribute electricity from solar powergeneration facility 210 and, likely, multiple other power generationfacilities to structures throughout a geographic region. To simplifyFIG. 2, electrical grid 230 is represented as a block and is shown asconnected with only a single structure 240. It should be understood thatelectrical grid 230, in a real-world environment, would be connectedwith tens of thousands of structures.

At structure 240, various systems may use electricity. Heating,ventilation, and air conditioning (HVAC) systems, if powered byelectricity, tend to use a significant amount. For instance, whenair-conditioning is being used, a structure's air-conditioner tends tobe the largest or one of the largest power draws within the structure.Similarly, if electrical heating is being used, electrical heat can bethe largest or one of the largest power draws within a structure. InFIG. 2, structure 240 has installed an electric air-conditioner 242 andan electric heater 244. It should be understood that in manyarrangements, only one of air-conditioner 242 and electric heater 244 ispresent.

Network-enabled smart thermostat 250-1 may control activation ofair-conditioner 242 and/or electric heater 244. Network-enabled smartthermostat 250-1 may be able to communicate with one or more remotecomputerized systems via an Internet connection represented by structure240 being connected with network 235. Network-enabled smart thermostat250-1 may be referred to herein as “smart” due to its ability (possiblyin addition to learning the preferences and habits of the occupants) tocommunicate with remote computerized systems and process and executecommands, at least some of which may be received from such remotecomputerized systems. For basic functionality, network-enabled smartthermostat 250-1 has stored a setpoint temperature which is indicativeof a temperature a user desires to be maintained within structure 240.In FIG. 2, network-enabled smart thermostat 250-1 is displaying adesired setpoint temperature of 68 degrees Fahrenheit. Network-enabledsmart thermostat 250-1 may control air-conditioner 242 and/or electricheater 244 as necessary in order to at least approximately realize thesetpoint temperature within the structure. Network-enabled smartthermostat 250-1 may have onboard one or more temperature sensors, oneor more user interfaces, one or more processors, an electronic display,and a wired or wireless network interface to allow for wirelesscommunication with a network access point.

While electric heater 244 may produce heat using electricity,solar-powered thermal energy storage system 200 may be functional withheating sources other than sources that directly produce heat fromelectricity. As an example, some gas and oil furnaces, especially oldersystems, may use an electric fan system that consumes a substantialamount of electricity. Despite such heating sources producing heat froma source other than electricity, the use of an accompanying electricdevice or system, such as an electric fan system, may consume asubstantial enough amount of electricity that using such an alternateheating system as part of solar-powered thermal energy storage system200 for preheating would be beneficial.

Thermal energy coordination system 220 may be in communication withsolar power generation facility 210, electrical grid 230, andnetwork-enabled smart thermostat 250-1. FIG. 2 depicts thermal energycoordination system 220 as being in direct communication with solarpower generation facility 210 and communicating with network-enabledsmart thermostat 250-1 via network 235. It should be understood thatthermal energy coordination system 220 may use network 235, which canrepresent the Internet, to also communicate with electrical grid 230 andsolar power generation facility 210.

Thermal energy coordination system 220 may include one or more computersystems that can coordinate transmission of one or more commands tonetwork-enabled smart thermostat 250-1 in order to heat or cool aninterior of structure 240 earlier and/or to a greater degree such that,at a later time, less demand will be placed on electrical grid 230 bysuch HVAC loads. For example, on a hot day, when a person returns fromwork, he may have set network-enabled smart thermostat 250-1 to coolstructure 240 to 68° F. by setting a corresponding setpoint that isactivated at, for example, 7 PM. If solar power generation facility 210is outputting sufficient electricity that there is spare capacitydetected, thermal energy coordination system 220 may causenetwork-enabled smart thermostat 250 to precool structure 240 (if theoutdoor temperature is above the desired setpoint and the airconditioner is activated) or preheat structure 240 (if the outdoortemperature is below the desired setpoint and the heater is activated)earlier than a time defined by the user's setpoint. Additionally oralternatively, structure 240 may be heated or cooled to a greater extentthan requested by the user setpoint. For example, if the outdoortemperature is above the desired setpoint, precooling may be performedto a lower temperature than 68° F. Alternatively, if the outdoortemperature is below the desired setpoint, preheating may be performedto a higher temperature than 68° F. While the remainder of this documentfocuses on precooling a structure to serve as thermal energy storage, itshould be understood that similar principles may be applied topreheating if the heating source is powered by or uses electricity.

Precooling structure 240, especially if well insulated, serves to storethermal energy which was created by air-conditioner 242 usingelectricity from electrical grid 230. Such electricity from electricalgrid 230 may have been received from solar power generation facility 210directly or may have been part of electricity generated by anotherelectricity producing facility due, at least in part, to increasedelectricity production by solar power generation facility 210 resultingin overgeneration. By energy being stored in the form of thermal energyby structure 240, a future demand placed upon electrical grid 230 bynetwork-enabled smart thermostat 250-1 may be decreased. For instance,since structure 240 has been precooled, during a later peak demandevent, network-enabled smart thermostat 250-1 may activateair-conditioner 242 a decreased amount of time or not at all. In someembodiments, the air conditioner being activated such a decreased amountof time may be based on a command received from thermal energycoordination system 220.

Based on information received from solar power generation facility 210,electrical grid 230 (e.g., current load data information), weatherpredictions (e.g., predicted cloud cover information), and/or othermeasurements, thermal energy coordination system 220 may be able todetermine when a likely overgeneration event is going to occur (that is,a time period during which excess electricity generation is going to bepresent due to solar panels converting a significant amount of solarenergy to electricity). Once an overgeneration event is predicted ordetected, thermal energy coordination system 220 may initiate a thermalenergy storage event and send an indication of such an event to variousnetwork-enabled smart thermostats such as network-enabled smartthermostat 250-1. Based on received indications of the thermal energystorage event, dozens, hundreds, or thousands of network-enabled smartthermostats may precool structures in which such thermostats areinstalled ahead of a demand event that is expected to be present onelectrical grid 230. By such a large number of structures beingprecooled, the demand placed for electricity on electrical grid 230 bysuch structures during the later peak demand event may be decreasedsignificantly. By precooling such structures, electricity is effectivelyused to “charge” the structures, which enables such structures to serveas energy storage devices. The energy is stored by such structures asthermal energy until the demand response event. During the demandresponse event, the thermal energy is then “discharged” by keeping thestructure cool and decreasing the amount of time that an air conditioner(and, possibly, fan system) is activated during the peak demand event.By precooling the structure during an overgeneration time period, thestructures effectively become energy storage devices.

Of note, in solar-powered thermal energy storage system 200, batteriesand/or capacitors may not be used to store electricity. That is, powergenerated by solar power generation facility 210 may not be stored ineither a structure level or grid level battery until such electricity isdesired to be used. Since such batteries may not be installed, costeffective, or otherwise available storage of electricity generatedduring a solar overgeneration event may be stored as thermal energywithin multiple structures.

FIG. 3 illustrates an embodiment of a solar-powered thermal energystorage system 300 that includes distributed solar panels. Solar-poweredthermal energy storage system 300 represents an alternate or moredetailed embodiment of solar-powered thermal energy storage system 200.In solar powered thermal energy storage system 300, in addition thesolar panels being present at solar power generation facility 210, somesolar panels or distributed at structures, such as structure 330-1 andstructure 330-2. Solar panels located at a structure, such as structure330-1, may directly power electrical devices at such structures if thedemand is present. If demand is not present, electricity may betransferred from such structures to electrical grid 230. Electricitygenerated by the distributed solar panels including the solar panels atstructures and at solar power generation facility 210 may be stored asthermal energy at one or more structures as cooled air.

Multiple pyranometers may be installed in the vicinity of solar panelsin order to determine an amount of solar radiance incident on such solarpanels. For instance, pyranometers may be distributed at solar powergeneration facility, such as pyranometer 310-1 and pyranometer 310-2 andmay also be distributed near solar panels installed at structures suchas pyranometer 310-3. In some situations, pyranometers or similarequipment may be installed in the path weather usually travels towardssuch solar panels, thus allowing predictions to be made on the amount ofsolar energy that will be converted to electricity. Such pyranometersmay be in communication with thermal energy coordination system 220 vianetwork 235 or direct communication to allow thermal energy coordinationsystem 220 to evaluate measurements of solar irradiance to determine orpredict overgeneration events due at least in part to solar energyproduction.

In some embodiments, in addition to or alternatively to receivingmeasurements from various pyranometers, thermal energy coordinationsystem 220 may use data from other sources to determine whether anovergeneration event is in progress or is predicted. Such other sourcesmay include measurements of the output voltage or output power from anyof the solar panels and weather forecasts. Data may additionally begathered from electrical grid 230 which may indicate the current loadbeing placed on the grid. Such data may provide information aboutspecific sub grids within electrical grid 230. For instance, even if anoverall load is low on electrical grid 230, a sub grid that is part ofelectrical grid 230 may be experiencing a high load and thus, it may notbe advisable to initiate a thermal energy storage event that involvesplacing additional strain on the highly-loaded sub-grid.

Thermal energy coordination system may have distinct componentsincluding: solar output evaluator 321, thermostat registration engine322, and thermal storage event engine 323. Such components may beimplemented using one or more computerized systems. Solar outputevaluator 321 may use measurements from pyranometers 310, voltage orpower outputs from solar panels located at solar power generationfacility 210 and/or distributed solar panels located at structures 330,weather forecasts, and/or any other available data used to forecast oridentify the amount of electricity being generated by solar panels.Thermal storage event engine 323 may be analyzing data received fromsolar output evaluator 321 in combination with current conditions orpredicted conditions on electrical grid 230 in order to assess whetheran overgeneration event is present or predicted, whether a demand eventis predicted for later in the day, and whether a thermal storage eventis advisable to implement. If advisable to implement, thermal storageevent engine 323 may alert some number of network-enabled smartthermostats 250 to initiate a thermal storage event.

Thermostat registration engine 322 may serve to register network-enabledsmart thermostats 250 to participate in thermal energy storage events.First, thermostat registration engine 322 may evaluate whether aparticular network-enabled smart thermostat is eligible to participate,such as based on a thermal mass of the structure in which the thermostatis installed. Such a thermal mass may be determined based on location bythe smart thermostat using information including: air conditionerruntime, inside temperature measurements, and outside temperature.Thermostat registration engine 322 may only permit network-enabled smartthermostats to participate in a thermal storage event if thecorresponding structure has at least a particular thermal mass. Thermalmass of a structure may be increased by addition of better and/or moreinsulation. Additionally or alternatively, even if a smart thermostat iseligible to register for inclusion in a thermal energy storage event,more smart thermostats may be registered that are permitted toparticipate in a given event, such as based on the amount of excesselectricity generated directly or indirectly by solar panels. In such asituation, smart thermostats associated with structures that have thehighest thermal mass may be selected for participation. Therefore, ifthe owner of a structure desires for his structure to participatefrequently in thermal energy storage events, the structure's thermalmass should be increased to a higher amount than other structures thatare also eligible to participate.

FIG. 4 illustrates another embodiment of a solar-powered thermal energystorage system 400 that uses a third-party platform to managecommunication with network-enabled smart thermostats. Solar-poweredthermal energy storage system 400 represents an alternate or moredetailed embodiment of solar-powered thermal energy storage system 300.Network-enabled smart thermostats may be configured such that they canonly communicate via network 235 with thermostat service provider system410. For example, thermostat service provider system 410 may be amanufacturer that sells network-enabled smart thermostats. In order topreserve security around privacy-sensitive data, network-enabled smartthermostats 250 may be configured to only communicate with thermostatservice provider system 410. Smart thermostats manufactured ordistributed by another service provider may similarly only communicatewith the corresponding thermostat service provider.

In such embodiments, rather than communicating directly withnetwork-enabled smart thermostats 250, thermal energy coordinationsystem 220 may communicate with thermostat service provider system 410(and, possibly one or more other thermostat service providers thathandle communication with other smart thermostats). When thermal energycoordination system 220 is initiating a thermal energy storage event, anindication of the thermal energy storage event and, possibly, theparticular network-enabled smart thermostats that are to participate inthe thermal energy storage event, may be transmitted to thermostatservice provider system 410 in a message or series of messages. Such amessage may indicate: a time period corresponding to a solarovergeneration event, a time period corresponding to a peak demandevent, and an identifier of the one or more smart thermostats toparticipate in the thermal storage event. In such embodiments,thermostat service provider system 410 may host one or more of thecomponents of thermal energy coordination system, such as thermostatregistration engine 322.

In FIGS. 3 and 4, electric air conditioning units and electric heatersare not illustrated for simplicity of the drawings. It should beunderstood that each of network-enabled smart thermostats 250 control atleast one of an air conditioner and an electric heater. If only an airconditioner is controlled by a smart thermostat, that structure andsmart thermostat is eligible to participate in only precooling-basedthermal energy storage events. If only an electric heater is controlledby a smart thermostat, that structure and smart thermostat is eligibleto participate in only preheating-based thermal energy storage events.

Various methods for using the systems of FIGS. 2-4 may be used toperform a thermal energy storage event that uses electricity generatedduring overgeneration that results directly or indirectly from a dailysolar peak event to help alleviate demand during a peak demand eventoccurring later the same day. The methods of FIGS. 5-8 may be performedusing the systems of FIGS. 2-4. It should be understood that suchmethods may also be performed using other systems that provide fortemporary thermal energy storage. FIG. 5 illustrates a method 500 forusing a thermal energy storage system. Each step of method 500 may beperformed by a thermal energy coordination system, such as thermalenergy coordination system 220 of FIG. 3.

At block 510, an amount of power generated during an overgenerationevent by or otherwise resulting from solar panels may be identified orpredicted. The amount of overgeneration power may include powergenerated at one or more solar power generation facilities and/or powergenerated using solar panels located at one or more structures. Theamount of power that is to be generated by the solar panel installationsover a period of time may be predicted based on: the time of the day,weather forecasts, historical data, solar intensity measurements, andvoltage/power outputs from such solar panel installations. Rather thanprediction, real-time measurements of power being generated by solarpanel installations may be used, such as based on solar intensitymeasurements and voltage/power outputs from such solar panelinstallations. To identify how much of the power generated is consideredovergeneration, the total available power output of sources of theelectrical grid may be compared with the current or predicted load onthe electrical grid. The difference between the load and the totalavailable power represents the overgeneration power. This overgenerationpower can be entirely or significantly attributed to the power generatedby the solar panel installations during the peak solar event because theamount of power generated by many other power sources (e.g., naturalgas, oil, nuclear, and coal) tend to remain fairly consistent, while theamount of power generated by solar panels greatly spikes during thehours of peak solar intensity. Therefore, during these hours, asignificant amount of overgeneration power attributed to the increase insolar power electricity production may be present.

At block 520, a demand event may be predicted. The demand event maytypically occur between 1 and 5 hours after a peak solar event. The peakdemand event may occur daily and may be predicted (in time ofoccurrence, duration, and in load spike) based on historical data, theweather (e.g., the temperature) and the day of the week (e.g., the peakdemand event may be more pronounced on a weekday).

At block 530, a thermal energy storage event may be activated. Thethermal energy storage event may be activated based on the demand eventbeing predicted at block 520 and the determined amount of overgenerationpower due to the use of solar panel installations at block 510. In someembodiments, the thermal energy storage event is only activated if thedemand event predicted at block 520 is greater than a deferred minimumthreshold. (That is, if the peak demand predicted for a day is below thethreshold, it may not be efficient to activate the thermal energystorage event.) Activation at block 530 may include identifying andselecting a set of network-enabled smart thermostats at which to executethe thermal energy storage event by precooling a structure'sinterior: 1) ahead of the peak demand event, which may result in auser's defined temperature setpoint being executed by the thermostatearlier than requested by a user; and/or 2) cooling the structure'sinterior to a lower temperature than requested by a user's setpoint. Bycooling the structure's interior to a lower temperature, the airconditioning at the structure may be activated less often such that atemperature in a vicinity of the user's desired setpoint is realizedduring the peak demand event. By cooling the structure's temperatureearly, power usage is shifted away from the peak demand event to insteadcoincide with the peak solar event.

At block 540, an indication of the thermal energy storage event may betransmitted to a set of network-enabled smart thermostats. In accordancewith systems 200 and 300 of FIGS. 2 and 3, respectively, the thermalenergy coordination system 220 may transmit this indication directly tovarious smart thermostats. Alternatively, in accordance with FIG. 4,thermal energy coordination system 220 may send the indication of thethermal energy storage event to one or more thermostat service providersystems, which may then format and relay appropriate instructions tonetwork-enabled smart thermostats 250. The indication at block 540 maybe a packetized message that includes all or a subset of the dataindicated in the example of Table 1.

It should also be understood that other embodiments of such anindication of a thermal energy storage event may include additional datatypes and values.

TABLE 1 Exemplary Message of Initialization of Thermal Energy StorageEvent Data Type Exemplary Value Network-Enabled Smart Thermostat Address2001:db8:a0b:12f0::1 Thermal Storage Event Activation YesPre-heating/Pre-cooling Pre-cooling Overgeneration Event Start 12:00Overgeneration Event End 16:00 Peak Demand Event Start 17:00 Peak DemandEvent End 21:00 Permitted Peak Demand Runtime 30 minutes

Based upon a network-enabled smart thermostat receiving an indication asexemplified in Table 1, the network-enabled smart thermostat may precoolthe structure in which it is installed during the overgeneration eventin order to thermally store energy for use later during the defined peakdemand event time period. The smart thermostat or a remote-server (e.g.,operated by the thermostat service provider) may calculate exactly whenand to what temperature precooling of the structure should be performedin order to realize power savings during the peak demand event based onthe thermal mass of the structure. A “permitted peak demand runtime” maybe indicated, which indicates an amount of time that the air conditioneris permitted to be operated during the peak demand event. By such a timeperiod being defined, the extent to which the structure is precooled canbe decreased. Greater precooling would be required to roughly maintain auser's desired temperature for the structure if, for example, thepermitted peak demand runtime was specified as zero, which correspondsto no operation of the air conditioner during the peak demand timeperiod.

FIG. 6 illustrates a method 600 for using a thermal energy storagesystem. At block 610, an amount of solar irradiance may be measured inthe vicinity of the one or more solar panel installations, which mayinclude a solar panel power generation facility and/or distributed solarpanels at structures that are connected with the electrical grid. One ormore pyranometers (e.g., pyranometers 310) may be used to determine asolar intensity that is currently being received by the solar panelinstallations. Data from such pyranometers, in combination with weatherdata, historical data, system operator data, voltage or powermeasurements from the solar panel installations, and/or the time may beused to determine and/or predict the solar irradiance that will bereceived by the solar panels that supply the grid with power for a giventime period.

At block 620, the measured and/or predicted solar irradiance measuredand/or predicted at block 610 is used to predict an overgenerationevent. Block 620 may be performed by, for example, solar outputevaluator 321, of thermal energy coordination system 220. Theovergeneration event may be determined according to equation 1:(Power_(PeakSolar)+Power_(Grid))−Load=Overgeneration   Eq. 1

In Equation 1, Power_(PeakSolar) represents the average amount of powerpredicted to be generated by solar panel installations connected withthe grid during the time period of a peak solar event. Power_(Grid)represents the average amount of power that is expected to be providedto the grid by the power sources other than the power sources includedin Power_(PeakSolar) during the peak solar event. Load represents theexpected load on the grid during the peak solar event. Overgenerationrepresents the amount of power that will be available on the grid duringthe peak solar event at least primarily due to the increased level ofpower production by the solar panel installations during the peak solarevent. Based on Equation 1, a percentage (e.g., 50%, 75%, 90%, 100%) ofOvergeneration may be allocated for use as part of a thermal energystorage event. In some embodiments, at least a portion of the analysisperformed at block 620 may be performed by an operator. That is, aperson may be presented with measured and/or predicted solar irradiancedata and may be permitted to make the ultimate decision as to whether anovergeneration solar power event is present. It should be understoodthat embodiments of method 600 may also be employed when anovergeneration of energy is not present.

A set of network-enabled smart thermostats at which to enable thethermal energy storage event may be selected at block 630. The selectionof the set may be made from a super set of smart thermostats that havebeen registered to be eligible to participate in thermal energy storageevents. Selection of the set of network-enabled smart thermostats may bebased on various factors, including: the size of the overgenerationidentified at block 620; the load on various sub-grids of the electricalgrid (that is, if the load during the solar overgeneration event on aparticular sub-grid of the electrical grid is already above or predictedto be above a defined threshold, structures that draw power from thatsub-grid may not be eligible to participate); and determined thermalmasses of the structures at which the network-enabled smart thermostatsare located (e.g., thermal mass may be required to be above a particularthreshold thermal mass value in order for the structure andnetwork-enabled smart thermostat to be eligible to participate, or thesmart thermostats associated with the highest thermal mass being givenpreference to participate). It may be desirable to limit an amount ofload on particular power substations during a peak demand event. Forsuch a situation, structures that receive power from that substation maybe targeted for inclusion in a thermal energy storage event. Conversely,it may be desirable to limit an amount of load on particular powersubstations during a peak solar event. For such a situation, structuresthat receive power from that substation may be targeted for exclusionfrom the thermal energy storage event.

An analysis of which thermostats to include or exclude on a sub-gridlevel basis may also be useful for providing one or more sub-grids withadditional voltage and/or frequency control. The ability to storeelectrical energy as thermal energy for use at a later time may beleveraged to improve voltage and frequency control on a sub-grid and,therefore, on the grid as a whole.

At block 640, a thermal energy storage event may be activated. Thethermal energy storage event may be activated by thermal storage eventengine 323 of thermal energy coordination system 220. The thermal energystorage event may be activated based on blocks 610-630. In someembodiments, the thermal energy storage event is only activated if thedemand event is predicted to involve greater than a defined threshold.If the peak demand predicted for a day is below a defined thresholddemand value, it may not be efficient to activate the thermal energystorage event. Activation at block 640 may include determining a timeperiod during which a peak demand event is likely to occur andpredicting the severity of the peak demand event. The greater theexpected load during the peak demand event, the greater theaggressiveness of an implemented thermal storage event. Greateraggressiveness may involve increasing the amount of thermal energystored and the shorter the amount of time that the smart thermostats arepermitted to activate the air conditioning during the peak demand event.

Activation at block 640 can include creating messages that includeinstructions for precooling a structure's interior: 1) ahead of the peakdemand event and/or 2) cooling the structure's interior to a lowertemperature than requested by a user-defined setpoint. By cooling thestructure's interior to a lower temperature, the air conditioner at thestructure may be activated less often such that a temperature roughlyequal to the user's desired setpoint is still realized during the peakdemand event without engaging the air conditioner. By cooling thestructure's temperature early, power usage is shifted away from the peakdemand event to instead coincide with the peak solar event.

At block 650, an indication of the thermal energy storage event may betransmitted to the set of network-enabled smart thermostats identifiedat block 630. In accordance with systems 200 and 300 of FIGS. 2 and 3,respectively, the thermal energy coordination system 220 may transmitthis indication directly to various smart thermostats. Alternatively, inaccordance with FIG. 4, thermal energy coordination system 220 may sendthe indication of the thermal energy storage event to one or morethermostat service provider systems, which may then format and relayappropriate instructions to network-enabled smart thermostats 250. Theindication at block 650 may be a packetized message that includes all ora subset of the data indicated in the example of Table 1. It should alsobe understood that other embodiments of such an indication of a thermalenergy storage event may include additional data types and values.

Various steps related to a thermal energy storage event may be performedby the individual smart thermostats, possibly in combination with athermostat service provider system. FIG. 7 illustrates an embodiment ofa method for a network-enabled smart thermostat to participate as partof a thermal energy storage system. At block 710, a smart thermostat orthermostat service provider system may receive an indication of thermalenergy storage event. The indication may be one or more messages,received via the Internet, that includes some or all of the informationindicated in Table 1.

At block 720, the network-enabled smart thermostats may precool thestructure in which the network-enabled smart thermostats are installedin accordance with the defined thermal energy storage event received atblock 710. The smart thermostat may cool the interior of the structureto a temperature significantly below a user's desired setpoint ahead ofa peak demand event. Such precooling may occur during a time perioddefined as a solar overgeneration event and the precooling may beperformed to a temperature that will likely result in the interior ofthe structure being kept within a defined range of degrees during thepeak demand event. To determine how much precooling is necessary, thethermal mass of the structure may be used by the network-enabledthermostat or the thermostat service provider system to calculate whenprecooling should begin and to what temperature precooling should beperformed. As an example, if a peak demand event is expected to occurfrom 7 PM until 8 PM, the overgeneration solar event occurs from 11 AMuntil 4 PM, and the setpoint at the user's structure calls for the houseto be kept cooled to 72 degrees during the 7 PM to 8 PM timeframe, thesmart thermostat or the thermostat service provider system may determinethat the structure should be called to 65° by 4 PM. By precooling tosuch a temperature, the structure may be kept relatively close to theuser's desired 72° setpoint during the 7 PM to 8 PM timeframe whilereducing or eliminating the amount of time during which the airconditioner is required to run during the peak demand event at block730, thus effectively storing thermal energy for use during the peakdemand event. In some embodiments, if the temperature of the structurerises a defined number of degrees above the user's desired setpointduring the peak demand event, the air conditioner may be activatedregardless of the thermal energy storage event in effect. In someembodiments, the thermal energy storage event may define a period oftime for which the air conditioner is permitted to be run during thepeak demand event. Further, in some embodiments, user is permitted tooverride participation in the thermal energy storage event and force thethermostat and air-conditioning to bring the structure to the user'sdesired setpoint temperature.

Based on the structure being pre-cooled at block 720 in accordance withthe thermal energy storage event, energy usage for cooling during thetime period designated as a peak demand event may be decreased oreliminated at block 730. For instance, in some embodiments, the airconditioner may be prohibited from turning on by the smart thermostatdue to the contents of the thermal energy storage event indicationreceived at block 710. In some embodiments, the smart thermostat or thethermostat service provider system may monitor the runtime of the airconditioner during the peak demand event. From such information, theeffectiveness of the thermal energy storage event at the structure maybe assessed. Information regarding: the air conditioning runtime,whether a user override was implemented, the temperature which thestructure was pre-cooled, the time at which the structure was precooled,thermal mass measures, and/or performance during the peak demand eventmay be provided to the thermal energy coordination system following theconclusion of the thermal energy storage event at block 740. Suchinformation may be used to configure future thermal energy storageevents and determine which network-enabled smart thermostats should beeligible to participate in such future events.

In order to participate in a thermal energy storage event, a smartthermostat may first need to register to be eligible to participate.Such eligibility may be at least partially determined based on a thermalmass of the structure in which the smart thermostat is installed. Thatis, it may only be efficient to implement a thermal energy storage eventin a well-insulated structure that can effectively maintain asignificant temperature differential between an internal and externalenvironment for a sufficient period of time, such as 4 hours. By onlymaking certain structures eligible, such as based on thermal mass,consumers may be encouraged to increase the level of insulation of theirhome or other structure. Such participation may have certain benefits,such as financial remuneration or discounts on electricity service.

FIG. 8 illustrates an embodiment of a method 800 for registering anetwork-enabled smart thermostat to participate as part of a thermalenergy storage system. At block 810, a smart thermostat may control anair conditioner that cools the interior of the structure. The smartthermostat may track internal measured temperatures of the structure andthe runtime of the air conditioner. Such information, in combinationwith outdoor temperature and/or weather information may be used todetermine a thermal mass of the structure. At block 820, the thermalmass of the structure may be calculated based on multiple cooling cyclesthat were controlled by the smart thermostat at block 810. In someembodiments, the information collected at block 810 may be transmittedto the thermostat service provider or to the thermal energy coordinationsystem for use in calculating the thermal mass of the structure. Forexample, in some embodiments, thermostat registration engine 322 may beused to register smart thermostats and/or calculate thermal mass ofstructures based on information received from smart thermostats.

Assuming the thermal mass is calculated at either the smart thermostator the thermostat service provider, the calculated thermal mass valuemay be transmitted to the thermal energy coordination system at block830. In such embodiments, thermostat registration engine 322 may receivethe thermal mass value along with an indication of the smart thermostatassociated with the value. Thermostat registration engine 322 may alsoreceive or request information about the smart thermostat, such as thelocation. Such location information may be used to determine whichsub-grid of the electrical grid the structure at which the smartthermostat is installed receives power from. Such information may beuseful in ensuring that no particular sub-grid of the electrical grid isoverloaded during a thermal energy storage event.

At block 840, the eligibility for the structure and the associated smartthermostat to participate as part of the thermal energy storage systemmay be assessed. In some embodiments, eligibility may be determined bythe thermostat registration engine of the thermal energy coordinationsystem based on the thermal mass for the structure being greater than apredefined threshold. In such embodiments, if the thermal mass of thestructure is above the threshold, the smart thermostat is eligible toparticipate. If not, the smart thermostat is ineligible. In otherembodiments, eligibility may be based upon the thermal mass value beinghigher than the thermal mass value of other structures. For instance,only the 10,000 structures with the highest thermal mass values thathave applied for eligibility may be permitted in the program. If a smartthermostat is enrolled in the program, a smart thermostat associatedwith a structure having a lower thermal mass may be removed from theprogram. In some embodiments, all smart thermostats are eligible;however, structures that have a lower thermal mass may be less likely tobe used during a thermal energy storage event. That is, a solarovergeneration event involves a finite amount of electricity beingavailable for use during a thermal energy storage event. This finiteamount of electricity may be allocated to invoke the thermal energystorage event at structures having the greatest thermal mass.

If block 840 proceeds to block 850, the smart thermostat and theassociated structure is enrolled as part of the thermal energy storagesystem. The thermal energy coordination system may store an indicationof the smart thermostat, such as an IP address, along with an indicationof the thermal mass associated with the smart thermostat. As such, thethermal energy coordination system may have access to a list of eligiblesmart thermostats along with associated thermal masses and may use suchassociated thermal masses when selecting thermostats to participate in athermal energy storage event. If block 840 proceeds to block 860, thethermal energy coordination system may provide the user via the smartthermostat (or via some other arrangement, such as via email) anindication as to the current ineligibility to participate in the thermalenergy storage system. Such a message of ineligibility may indicate thereason for eligibility, such as the particular sub-grid to which theuser's structure is connected has too high of load when overgenerationevents typically occur or an indication that the thermal mass of theuser's structure is insufficient and, possibly, that if the userimproved insulation of the structure, the structure may become eligibleto participate and may also be more comfortable for occupants.Additional information may also be provided to an associated user if astructure is found to be ineligible. For instance, a smart thermostatmay display information about a person or company that the user cancontact about increasing the insulation of his home, such as a privatecompany that specializes in structure insulation or a public entity thathelps occupants increase their structure's efficiency. The smartthermostat may also provide the user with an estimate of the cost to addsufficient insulation to qualify for thermal energy storage events. Suchan estimate may be based on the minimum thermal mass needed to qualifyfor the program, the structure's current thermal mass, and coststypically associated with increasing a structure's thermal mass by theamount indicated by the difference between the structure's currentthermal mass and the minimum thermal mass needed to qualify toparticipate in the program. Such information may be provided to the userin ways other than on a display of the smart thermostat. For instance,an email or a letter may be used provide such information.

A computer system as illustrated in FIG. 9 may be incorporated as partof the previously described computerized devices, such as the thermalenergy coordination systems, and the network-enabled smart thermostats.FIG. 9 provides a schematic illustration of one embodiment of a computersystem 900 that can perform various steps of the methods provided byvarious embodiments. It should be noted that FIG. 9 is meant only toprovide a generalized illustration of various components, any or all ofwhich may be utilized as appropriate. FIG. 9, therefore, broadlyillustrates how individual system elements may be implemented in arelatively separated or relatively more integrated manner.

The computer system 900 is shown comprising hardware elements that canbe electrically coupled via a bus 905 (or may otherwise be incommunication). The hardware elements may include one or more processors910, including without limitation one or more general-purpose processorsand/or one or more special-purpose processors (such as digital signalprocessing chips, graphics acceleration processors, video decoders,and/or the like); one or more input devices 915, which can includewithout limitation a mouse, a touchscreen, keyboard, remote control,and/or the like; and one or more output devices 920, which can includewithout limitation a display device, a printer, etc.

The computer system 900 may further include (and/or be in communicationwith) one or more non-transitory storage devices 925, which cancomprise, without limitation, local and/or network accessible storage,and/or can include, without limitation, a disk drive, a drive array, anoptical storage device, a solid-state storage device, such as a solidstate drive (“SSD”), random access memory (“RAM”), and/or a read-onlymemory (“ROM”), which can be programmable, flash-updateable and/or thelike. Such storage devices may be configured to implement anyappropriate data stores, including without limitation, various filesystems, database structures, and/or the like.

The computer system 900 might also include a communications subsystem930, which can include without limitation a modem, a network card(wireless or wired), an infrared communication device, a wirelesscommunication device, and/or a chipset (such as a Bluetooth™ device,BLE, an 802.11 device, an 802.15.4 device, a WiFi device, a WiMaxdevice, cellular communication device, etc.), and/or the like. Thecommunications subsystem 930 may permit data to be exchanged with anetwork (such as the network described below, to name one example),other computer systems, and/or any other devices described herein. Inmany embodiments, the computer system 900 will further comprise aworking memory 935, which can include a RAM or ROM device, as describedabove.

The computer system 900 also can comprise software elements, shown asbeing currently located within the working memory 935, including anoperating system 940, device drivers, executable libraries, and/or othercode, such as one or more application programs 945, which may comprisecomputer programs provided by various embodiments, and/or may bedesigned to implement methods, and/or configure systems, provided byother embodiments, as described herein. Merely by way of example, one ormore procedures described with respect to the method(s) discussed abovemight be implemented as code and/or instructions executable by acomputer (and/or a processor within a computer); in an aspect, then,such code and/or instructions can be used to configure and/or adapt ageneral purpose computer (or other device) to perform one or moreoperations in accordance with the described methods.

A set of these instructions and/or code might be stored on anon-transitory computer-readable storage medium, such as thenon-transitory storage device(s) 925 described above. In some cases, thestorage medium might be incorporated within a computer system, such ascomputer system 900. In other embodiments, the storage medium might beseparate from a computer system (e.g., a removable medium, such as acompact disc), and/or provided in an installation package, such that thestorage medium can be used to program, configure, and/or adapt a generalpurpose computer with the instructions/code stored thereon. Theseinstructions might take the form of executable code, which is executableby the computer system 900 and/or might take the form of source and/orinstallable code, which, upon compilation and/or installation on thecomputer system 900 (e.g., using any of a variety of generally availablecompilers, installation programs, compression/decompression utilities,etc.), then takes the form of executable code.

It will be apparent to those skilled in the art that substantialvariations may be made in accordance with specific requirements. Forexample, customized hardware might also be used, and/or particularelements might be implemented in hardware, software (including portablesoftware, such as applets, etc.), or both. Further, connection to othercomputing devices such as network input/output devices may be employed.

As mentioned above, in one aspect, some embodiments may employ acomputer system (such as the computer system 900) to perform methods inaccordance with various embodiments of the invention. According to a setof embodiments, some or all of the procedures of such methods areperformed by the computer system 900 in response to processor 910executing one or more sequences of one or more instructions (which mightbe incorporated into the operating system 940 and/or other code, such asan application program 945) contained in the working memory 935. Suchinstructions may be read into the working memory 935 from anothercomputer-readable medium, such as one or more of the non-transitorystorage device(s) 925. Merely by way of example, execution of thesequences of instructions contained in the working memory 935 mightcause the processor(s) 910 to perform one or more procedures of themethods described herein.

The terms “machine-readable medium,” “computer-readable storage medium”and “computer-readable medium,” as used herein, refer to any medium thatparticipates in providing data that causes a machine to operate in aspecific fashion. These mediums may be non-transitory. In an embodimentimplemented using the computer system 900, various computer-readablemedia might be involved in providing instructions/code to processor(s)910 for execution and/or might be used to store and/or carry suchinstructions/code. In many implementations, a computer-readable mediumis a physical and/or tangible storage medium. Such a medium may take theform of a non-volatile media or volatile media. Non-volatile mediainclude, for example, optical and/or magnetic disks, such as thenon-transitory storage device(s) 925. Volatile media include, withoutlimitation, dynamic memory, such as the working memory 935.

Common forms of physical and/or tangible computer-readable mediainclude, for example, a floppy disk, a flexible disk, hard disk,magnetic tape, or any other magnetic medium, a CD-ROM, any other opticalmedium, any other physical medium with patterns of marks, a RAM, a PROM,EPROM, a FLASH-EPROM, any other memory chip or cartridge, or any othermedium from which a computer can read instructions and/or code.

Various forms of computer-readable media may be involved in carrying oneor more sequences of one or more instructions to the processor(s) 910for execution. Merely by way of example, the instructions may initiallybe carried on a magnetic disk and/or optical disc of a remote computer.A remote computer might load the instructions into its dynamic memoryand send the instructions as signals over a transmission medium to bereceived and/or executed by the computer system 900.

The communications subsystem 930 (and/or components thereof) generallywill receive signals, and the bus 905 then might carry the signals(and/or the data, instructions, etc. carried by the signals) to theworking memory 935, from which the processor(s) 910 retrieves andexecutes the instructions. The instructions received by the workingmemory 935 may optionally be stored on a non-transitory storage device925 either before or after execution by the processor(s) 910.

It should be further understood that the components of computer system900 can be distributed across a network. For example, some processingmay be performed in one location using a first processor while otherprocessing may be performed by another processor remote from the firstprocessor. Other components of computer system 900 may be similarlydistributed. As such, computer system 900 may be interpreted as adistributed computing system that performs processing in multiplelocations. In some instances, computer system 900 may be interpreted asa single computing device, such as a distinct laptop, desktop computer,or the like, depending on the context.

The methods, systems, and devices discussed above are examples. Variousconfigurations may omit, substitute, or add various procedures orcomponents as appropriate. For instance, in alternative configurations,the methods may be performed in an order different from that described,and/or various stages may be added, omitted, and/or combined. Also,features described with respect to certain configurations may becombined in various other configurations. Different aspects and elementsof the configurations may be combined in a similar manner. Also,technology evolves and, thus, many of the elements are examples and donot limit the scope of the disclosure or claims.

Specific details are given in the description to provide a thoroughunderstanding of example configurations (including implementations).However, configurations may be practiced without these specific details.For example, well-known circuits, processes, algorithms, structures, andtechniques have been shown without unnecessary detail in order to avoidobscuring the configurations. This description provides exampleconfigurations only, and does not limit the scope, applicability, orconfigurations of the claims. Rather, the preceding description of theconfigurations will provide those skilled in the art with an enablingdescription for implementing described techniques. Various changes maybe made in the function and arrangement of elements without departingfrom the spirit or scope of the disclosure.

Also, configurations may be described as a process which is depicted asa flow diagram or block diagram. Although each may describe theoperations as a sequential process, many of the operations can beperformed in parallel or concurrently. In addition, the order of theoperations may be rearranged. A process may have additional steps notincluded in the figure. Furthermore, examples of the methods may beimplemented by hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware, or microcode, the programcode or code segments to perform the necessary tasks may be stored in anon-transitory computer-readable medium such as a storage medium.Processors may perform the described tasks.

Having described several example configurations, various modifications,alternative constructions, and equivalents may be used without departingfrom the spirit of the disclosure. For example, the above elements maybe components of a larger system, wherein other rules may takeprecedence over or otherwise modify the application of the invention.Also, a number of steps may be undertaken before, during, or after theabove elements are considered.

What is claimed is:
 1. A thermal energy storage system, comprising: aplurality of pyranometers, wherein the plurality of pyranometers arephysically distributed in a vicinity of a plurality of solar panels, theplurality of pyranometers supplying a thermal energy coordination systemwith a plurality of solar irradiance measurements; the thermal energycoordination system, configured to: receive the plurality of solarirradiance measurements; analyze the plurality of solar irradiancemeasurements to predict an overgeneration solar energy event; activate,to coincide with the overgeneration solar energy event, a thermal energystorage event, the thermal energy storage event defining a time periodof the overgeneration solar energy event; and transmit, to at least asubset of a plurality of network-enabled smart thermostats, theindication of the thermal energy storage event in response to activatingthe thermal energy storage event; and the plurality of network-enabledsmart thermostats installed at a plurality of structures, wherein eachnetwork-enabled smart thermostat of the plurality of network-enabledsmart thermostats is configured to: control an air conditioner within astructure in which the network-enabled smart thermostat is installedbased upon a measured temperature and a setpoint temperature; determinea time to initiate cooling and a temperature to which to cool thestructure based upon the time period of the overgeneration solar energyevent; and initiate cooling by the air conditioner based on thedetermined time and the determined temperature in response to thereceived indication of the thermal energy storage event.
 2. The thermalenergy storage system of claim 1, wherein the thermal energycoordination system is configured to predict a time period during whichthe overgeneration solar energy event will occur at least partiallybased on the plurality of solar irradiance measurements, wherein theindication of the thermal energy storage event indicates the time. 3.The thermal energy storage system of claim 1, wherein electricitygenerated by the plurality of solar panels are used to directly powerair conditioners controlled by the plurality of network-enabled smartthermostats without using a battery charged by one or more solar panelsof the plurality of solar panels for storage of the electricity.
 4. Thethermal energy storage system of claim 1, wherein: each network-enabledsmart thermostat of the plurality of network-enabled smart thermostatsare further configured to transmit a thermal mass value to the thermalenergy coordination system such that the thermal energy coordinationsystem receives a plurality of thermal mass values from the plurality ofnetwork-enabled smart thermostats; and the thermal energy coordinationsystem is configured to select the subset of the plurality ofnetwork-enabled smart thermostats based on the plurality of thermal massvalues.
 5. The thermal energy storage system of claim 1, wherein: thethermal energy storage event indicates a time period during which anamount of energy used for cooling by the subset of the plurality ofnetwork-enabled smart thermostats is to be decreased; and eachnetwork-enabled smart thermostat of the plurality of network-enabledsmart thermostats is configured to: decrease a runtime of the airconditioner controlled by the network-enabled smart thermostat duringthe time period.
 6. The thermal energy storage system of claim 5,wherein each network-enabled smart thermostat of the plurality ofnetwork-enabled smart thermostats is further configured to ceaseactivating the air conditioner controlled by the network-enabled smartthermostat during the time period.
 7. The thermal energy storage systemof claim 1, wherein the plurality of solar panels comprise: a firstsubset of solar panels located at a grid-level solar facility and asecond subset of solar panels that are located at some structures of theplurality of structures.
 8. The thermal energy storage system of claim1, wherein the thermal energy coordination system being configured toactivate the thermal energy storage event is based on a differencebetween electricity generation by the plurality of solar panels and agrid electrical load.
 9. The thermal energy storage system of claim 1,wherein the thermal energy coordination system is further configured to:receive, from each network-enabled smart thermostat of a superset ofnetwork-enabled smart thermostats that comprises the plurality ofnetwork-enabled smart thermostats, a thermal mass value for thestructure at which the network-enabled smart thermostat is installed,such that the thermal energy coordination system receives a plurality ofthermal mass values from the superset of network-enabled smartthermostats; and select the plurality of network-enabled smartthermostats from the superset as eligible to participate as part of thethermal energy storage system based on the received plurality of thermalmass values.
 10. A method for using a thermal energy coordination serversystem, the method comprising: identifying, by the thermal energycoordination server system, a power overgeneration event that includespower overgeneration due at least in part to power generated by aplurality of solar panels; predicting, by the thermal energycoordination server system, a peak demand event expected to occur lateron a same day as the power overgeneration event; activating, before orduring the power overgeneration event, a thermal energy storage event inresponse to the power overgeneration event and prediction of the peakdemand event expected to occur on the same day; and transmitting, by thethermal energy coordination server system, to at least a subset of aplurality of network-enabled smart thermostats, an indication of thethermal energy storage event in response to activating the thermalenergy storage event, wherein: the thermal energy storage eventcomprises an indication of a first time period of the powerovergeneration event and an indication a second time period of the peakdemand event, and the first time period is used to store thermal energyuntil during the second time period.
 11. The method for using thethermal energy coordination server system of claim 10, furthercomprising: determining, by each network-enabled smart thermostat of atleast the subset of the plurality of network-enabled smart thermostats,a time to initiate cooling and a temperature to which to cool anassociated structure based upon the received indication of the thermalenergy storage event.
 12. The method for using the thermal energycoordination server system of claim 11, further comprising: initiating,by each network-enabled smart thermostat of at least the subset of theplurality of network-enabled smart thermostats, using an associated airconditioner, cooling based on the determined time and the determinedtemperature in response to the received indication of the thermal energystorage event.
 13. The method for using the thermal energy coordinationserver system of claim 10, wherein identifying the power overgenerationevent comprises analyzing, by the thermal energy coordination serversystem, a plurality of solar irradiance measurements to determine thefirst time period during which the power overgeneration event willoccur.
 14. The method for using the thermal energy coordination serversystem of claim 10, further comprising: receiving, by the thermal energycoordination server system, from each network-enabled smart thermostatof the plurality of network-enabled smart thermostats, a thermal massvalue such that the thermal energy coordination server system receives aplurality of thermal mass values from the plurality of network-enabledsmart thermostats; and selecting, by the thermal energy coordinationserver system, the subset of the plurality of network-enabled smartthermostats based on the plurality of thermal mass values.
 15. Themethod for using the thermal energy coordination server system of claim10, further comprising: ceasing, by each network-enabled smartthermostat of at least the subset of the plurality of network-enabledsmart thermostats, to activate an air conditioner controlled by thenetwork-enabled smart thermostat during the second time period of thepeak demand event in response to the received thermal energy storageevent.
 16. The method for using the thermal energy coordination serversystem of claim 10, wherein identifying the power overgeneration eventcomprises determining a difference between a predicted electricitygeneration amount and a predicted grid electrical load.
 17. The methodfor using the thermal energy coordination server system of claim 10,further comprising: receiving, from each network-enabled smartthermostat of a superset of network-enabled smart thermostats, a thermalmass value for a structure at which the network-enabled smart thermostatis installed, such that the thermal energy coordination server systemreceives a plurality of thermal mass values from the superset ofnetwork-enabled smart thermostats; and selecting, by the thermal energycoordination server system, the plurality of network-enabled smartthermostats from the superset as eligible to participate as part of thethermal energy coordination server system based on the receivedplurality of thermal mass values.
 18. A non-transitoryprocessor-readable medium comprising processor-readable instructionsconfigured to cause one or more processors to: identify a powerovergeneration event expected to occur that includes powerovergeneration due at least in part to power generated by a plurality ofsolar panels; identify a peak demand event expected to occur later on asame day as the power overgeneration event; activate a thermal energystorage event in response to the identified power overgeneration eventand the identified peak demand event expected to occur on the same day;and transmit to a subset of a plurality of network-enabled smartthermostats, an indication of the thermal energy storage event inresponse to activating the thermal energy storage event, wherein: thethermal energy storage event comprises an indication of a first timeperiod of the power overgeneration event and an indication a second timeperiod of the peak demand event, and the first time period is used tostore thermal energy until during the second time period.
 19. Thenon-transitory processor-readable medium of claim 18, wherein theprocessor-readable instructions configured to cause the one or moreprocessors to identify the power overgeneration event compriseprocessor-readable instructions configured to cause the one or moreprocessors to: analyze a plurality of solar irradiance measurements todetermine the first time period during which the power overgenerationevent is expected to occur.
 20. The non-transitory processor-readablemedium of claim 18, wherein the processor-readable instructions arefurther configured to cause the one or more processors to: receive, fromeach network-enabled smart thermostat of the plurality ofnetwork-enabled smart thermostats, a thermal mass value such that athermal energy coordination system receives a plurality of thermal massvalues from the plurality of network-enabled smart thermostats; andselect the subset of the plurality of network-enabled smart thermostatsusing the plurality of thermal mass values.